Methods and devices for beam failure recovery

ABSTRACT

A method (100) in a network device for configuration of Beam Failure Recovery, BFR. The method (100) includes: receiving (110) from a terminal device a beam failure report associated with a Secondary Cell, SCell. The method (100) further includes: configuring (120) the terminal device with at least one of the following BFR options: BFR with Physical Uplink Control Channel, PUCCH, BFR with Contention Free Random Access, CFRA, BFR with Contention Based Random Access, CBRA, and BFR without Physical Random Access Channel, PRACH, and PUCCH.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of Ser. No. 16/968,699, filed on Aug.10, 2020 (status pending), which is a 35 U.S.C. § 371 National Stage ofInternational Patent Application No. PCT/CN2019/074789, filed Feb. 11,2019, which claims priority to PCT/CN2018/076316, filed Feb. 11, 2018.The above identified applications are incorporated by this reference.

TECHNICAL FIELD

The present disclosure relates to wireless communications, and moreparticularly, to methods and devices for Beam Failure Recovery (BFR).

BACKGROUND

In New Radio (NR), beam based radio link maintenance is adopted. Thereare both radio link maintenance and beam link maintenance in the NR.

The radio link maintenance can be achieved based on a radio linkmonitoring procedure. A Radio Link Failure (RLF) can be detected at aterminal device based on a number of measurements such as hypotheticalPhysical Downlink Control Channel (PDCCH) Block Error Rate (BLER), RadioLink Control (RLC) retransmissions in RLC acknowledgement mode and afailure of random access to a target cell during handover. An RLF canalso be detected at a network device (e.g., a gNB) based on e.g. a pooruplink radio channel quality.

When an RLF is detected, a terminal device will release configured radioresources such as Physical Uplink Control Channel (PUCCH), configuredsemi-static uplink grants or downlink assignments, Channel StateInformation-Reference Signals (CSI-RSs), Sounding Reference Signals(SRSs), Demodulation Reference Signals (DMRS), etc., skip dynamic grantsfrom its serving cell, and start a radio connection re-establishmentprocedure. In the radio connection re-establishment procedure, theterminal device first selects a target cell and then performs a randomaccess to the cell. A Cell-Radio Network Temporary Identifier (C-RNTI)can be reported in Message 3 via a Medium Access Control (MAC) ControlElement (CE) so that the target cell can identify the terminal deviceand retrieve the UE context. Once the random access has succeeded, radioresources can be reconfigured for the terminal device.

For the beam link maintenance, a terminal device can monitor a beam linkquality based on hypothetical PDCCH BLER as well. For example, a beamfailure can be detected when a beam link quality is worse than apreconfigured threshold for a number of times. Unlike the above scenarioof RLF, when a beam failure is detected, the terminal device will notrelease configured resources (such as PUCCH resources, CSI-RSs, SRSs,DMRSs, PDCCH resources and configured uplink grants and/or downlinkassignments). In this case, the terminal device can perform a BeamFailure Recovery (BFR) procedure, including BFR with PUCCH, BFR withContention Based Random Access (CBRA) or BFR with Contention Free RandomAccess (CFRA). For details of the BFR with PUCCH and the BFR with CFRA,reference can be made to Final Report of 3GPP TSG RAN WG1 #89, v1.0.0,3GPP TSG RAN WG1 Meeting #90, R1-1712031, Prague, Czech Rep, 21-25 Aug.2017; and for details of the BFR with CBRA, reference can be made toReport from LTE and NR User Plane Break-Out Session, 3GPP TSG-RAN WG2Meeting #100, R2-1714117, Reno, USA, 27 Nov.-1 Dec. 2017, bothincorporated herein by reference.

Moreover, a Carrier Aggregation feature will be supported in the NR. Aterminal device can be configured with e.g., up to 16 carriers,including one Primary Cell (PCell) and one or more Secondary Cells(SCells). When a beam failure occurs in an SCell, the terminal devicemay not be able to transmit or receive data in that SCell.

It is thus desired to perform BFR for SCells.

SUMMARY

It is an object of the present disclosure to provide methods and devicesfor BFR for an SCell.

According to a first aspect of the present disclosure, a method in anetwork device for configuration of Beam Failure Recovery (BFR) isprovided. The method includes: receiving from a terminal device a beamfailure report associated with a Secondary Cell (SCell). The methodfurther includes: configuring the terminal device with at least one ofthe following BFR options: BFR with Physical Uplink Control Channel(PUCCH), BFR with Contention Free Random Access (CFRA), BFR withContention Based Random Access (CBRA), and BFR without Physical RandomAccess Channel (PRACH) and PUCCH.

In an embodiment, the method may further include: transmitting to theterminal device an acknowledgement of receipt of the beam failurereport.

In an embodiment, the at least one BFR option may be configured in theacknowledgement.

In an embodiment, the acknowledgement may indicate one or more of: anindex or Cell/Carrier Indicator Flag (CIF) of the SCell, an index of acandidate beam recommended for BFR, an indicator of one of the BFRoptions; a PUCCH resource when the BFR with PUCCH is configured, or aPRACH resource when the BFR with CFRA is configured, and an index of aserving cell in which the terminal device is to perform the BFR, and/orwhen a Supplementary Uplink (SUL) carrier is configured for that servingcell, an indication of whether the SUL carrier is to be used for theBFR.

In an embodiment, the method may further include: configuring theterminal device with a PUCCH resource pool via Radio Resource Control(RRC) signaling. The acknowledgement indicating a PUCCH resourceincludes: the acknowledgement indicating a PUCCH resource in the PUCCHresource pool.

In an embodiment, the acknowledgement may be transmitted in a MediumAccess Control (MAC) Control Element (CE).

In an embodiment, the acknowledgement may be transmitted in one singleMAC CE along with another acknowledgement of receipt of another beamfailure report associated with another SCell.

In an embodiment, the acknowledgement may be transmitted via RRCsignaling.

In an embodiment, the acknowledgement may be transmitted as a MAC CEthat is identified by a MAC Protocol Data Unit (PDU) sub-header with apredefined Logic Channel Identifier (LCID) and has a null payload.

In an embodiment, the at least one BFR option may be configured via RRCsignaling.

In an embodiment, the acknowledgement may be transmitted in a PrimaryCell (PCell), a PUCCH SCell, or an SCell with a configured downlink.

In an embodiment, the method may further include configuring theterminal device with a BFR priority for each serving cell based on atleast one of: a carrier frequency of that serving cell, a numerology ortransmission duration of that serving cell, a service or logical channelassociated with or mapped to that serving cell, a traffic load in thatserving cell and whether the serving cell is a PUCCH SCell.

According to a second aspect of the present disclosure, a network deviceis provided. The network device includes a transceiver, a processor anda memory. The memory includes instructions executable by the processorwhereby the network device is operative to perform the method accordingto the above first aspect.

According to a third aspect of the present disclosure, a computerreadable storage medium is provided. The computer readable storagemedium has computer program instructions stored thereon. The computerprogram instructions, when executed by a processor in a network device,cause the network device to perform the method according to the abovefirst aspect.

According to a fourth aspect of the present disclosure, a method in aterminal device for Beam Failure Recovery (BFR) is provided. The methodincludes: detecting a beam failure associated with a Secondary Cell(SCell); and transmitting to a network device a beam failure reportassociated with the beam failure. The method further includes: receivinga configuration of at least one of the following BFR options: BFR withPhysical Uplink Control Channel (PUCCH), BFR with Contention Free RandomAccess (CFRA), BFR with Contention Based Random Access (CBRA), and BFRwithout Physical Random Access Channel (PRACH) and PUCCH; and performinga BFR in accordance with the at least one BFR option.

In an embodiment, the method may further include: receiving from thenetwork device an acknowledgement of receipt of the beam failure report.

In an embodiment, the configuration of the at least one BFR option maybe received in the acknowledgement.

In an embodiment, the acknowledgement may indicate one or more of: anindex or Cell/Carrier Indicator Flag (CIF) of the SCell, an index of acandidate beam recommended for BFR, an indicator of one of the BFRoptions; a PUCCH resource when the BFR with PUCCH is configured, or aPRACH resource when the BFR with CFRA is configured, and an index of aserving cell in which the terminal device is to perform the BFR, and/orwhen a Supplementary Uplink (SUL) carrier is configured for that servingcell, an indication of whether the SUL carrier is to be used for theBFR.

In an embodiment, the method may further include: receiving from thenetwork device a configuration of a PUCCH resource pool via RadioResource Control (RRC) signaling. The acknowledgement indicating a PUCCHresource includes: the acknowledgement indicating a PUCCH resource inthe PUCCH resource pool.

In an embodiment, the acknowledgement may be received in a Medium AccessControl, (MAC) Control Element (CE).

In an embodiment, the acknowledgement may be received in one single MACCE along with another acknowledgement of receipt of another beam failurereport associated with another SCell.

In an embodiment, the acknowledgement may be received via RRC signaling.

In an embodiment, the acknowledgement may be received as a MAC CE thatis identified by a MAC Protocol Data Unit (PDU) sub-header with apredefined Logic Channel Identifier (LCID) and has a null payload.

In an embodiment, the configuration of the at least one BFR option maybe received via RRC signaling.

In an embodiment, the acknowledgement may be received in a Primary Cell(PCell), a PUCCH SCell, or an SCell with a configured downlink.

In an embodiment, when the BFR is performed in accordance with the BFRwithout PRACH and PUCCH, the BFR may be performed in the SCell and themethod may further include: determining whether the BFR has succeededbased on a downlink or uplink data transmission in the SCell.

In an embodiment, the operation of determining whether the BFR hassucceeded based on a downlink data transmission in the SCell mayinclude: receiving a downlink data over a Physical Downlink SharedChannel (PDSCH); transmitting a Hybrid Automatic Repeat reQuest (HARD)Acknowledgement (ACK) or Non-Acknowledgement (NACK) over PUCCH inresponse to the downlink data; and determining, when an ACK istransmitted, that the BFR has succeeded when no further PhysicalDownlink Control Channel (PDCCH) is received for schedulingretransmission of the downlink data, or determining, when a NACK istransmitted, that the BFR has succeeded when Downlink ControlInformation (DCI) is received for scheduling retransmission of thedownlink data with a redundancy version value different from an initialvalue or without New Data Indication (NDI) toggling.

In an embodiment, the operation of determining whether the BFR hassucceeded based on an uplink data transmission in the SCell may include:transmitting an uplink data over a Physical Uplink Shared Channel(PUSCH); and determining that the BFR has succeeded when no DownlinkControl Information (DCI) is received for scheduling retransmission ofthe uplink data within a predetermined time period, or DCI is receivedfor scheduling retransmission of the uplink data with a redundancyversion value different from an initial value or without New DataIndication (NDI) toggling.

In an embodiment, the method may further include: receiving from thenetwork device a configuration of a BFR priority for each serving celldependent on at least one of: a carrier frequency of that serving cell,a numerology or transmission duration of that serving cell, a service orlogical channel associated with or mapped to that serving cell, atraffic load in that serving cell and whether the serving cell is aPUCCH SCell.

In an embodiment, the method may further include: prior to transmittingthe beam failure report: transmitting to the network device a PUCCHScheduling Request (SR) for requesting an uplink grant for transmissionof the beam failure report.

In an embodiment, the method may further include: starting a timerassociated with the acknowledgement when the beam failure report istransmitted; and retransmitting the beam failure report upon expiry ofthe timer.

According to a fifth aspect of the present disclosure, a terminal deviceis provided. The terminal device includes a transceiver, a processor anda memory. The memory includes instructions executable by the processorwhereby the terminal device is operative to perform the method accordingto the above fourth aspect.

According to a sixth aspect of the present disclosure, a computerreadable storage medium is provided. The computer readable storagemedium has computer program instructions stored thereon. The computerprogram instructions, when executed by a processor in a terminal device,cause the terminal device to perform the method according to the abovefourth aspect.

With the above embodiments, a network device can configure a terminaldevice with one or more BFR options, including BFR with PUCCH, BFR withCFRA, BFR with CBRA, and BFR without PRACH and PUCCH. Accordingly, whenthe terminal device detects a beam failure in an SCell, it can performBFR in accordance with the configured BFR option. With configurable BFRoptions, it is possible to reduce PRACH load in a PCell.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages will be moreapparent from the following description of embodiments with reference tothe figures, in which:

FIG. 1 is a flowchart illustrating a method in a network device forcontrol of BWP switching according to an embodiment of the presentdisclosure;

FIG. 2 is a flowchart illustrating a method in a terminal device forcontrol of BWP switching according to an embodiment of the presentdisclosure;

FIG. 3 is a block diagram of a network device according to an embodimentof the present disclosure;

FIG. 4 is a block diagram of a network device according to anotherembodiment of the present disclosure;

FIG. 5 is a block diagram of a terminal device according to anembodiment of the present disclosure;

FIG. 6 is a block diagram of a terminal device according to anotherembodiment of the present disclosure;

FIG. 7 schematically illustrates a telecommunication network connectedvia an intermediate network to a host computer;

FIG. 8 is a generalized block diagram of a host computer communicatingvia a base station with a user equipment over a partially wirelessconnection; and

FIGS. 9 to 12 are flowcharts illustrating methods implemented in acommunication system including a host computer, a base station and auser equipment.

DETAILED DESCRIPTION

As used herein, the term “wireless communication network” refers to anetwork following any suitable communication standards, such asLTE-Advanced (LTE-A), LTE, Wideband Code Division Multiple Access(WCDMA), High-Speed Packet Access (HSPA), and so on. Furthermore, thecommunications between a terminal device and a network device in thewireless communication network may be performed according to anysuitable generation communication protocols, including, but not limitedto, Global System for Mobile Communications (GSM), Universal MobileTelecommunications System (UMTS), Long Term Evolution (LTE), and/orother suitable 1G (the first generation), 2G (the second generation),2.5G, 2.75G, 3G (the third generation), 4G (the fourth generation),4.5G, 5G (the fifth generation) communication protocols, wireless localarea network (WLAN) standards, such as the IEEE 802.11 standards; and/orany other appropriate wireless communication standard, such as theWorldwide Interoperability for Microwave Access (WiMax), Bluetooth,and/or ZigBee standards, and/or any other protocols either currentlyknown or to be developed in the future.

The term “network device” refers to a device in a wireless communicationnetwork via which a terminal device accesses the network and receivesservices therefrom. The network device refers to a base station (BS), anaccess point (AP), or any other suitable device in the wirelesscommunication network. The BS may be, for example, a node B (NodeB orNB), an evolved NodeB (eNodeB or eNB), or gNB, a Remote Radio Unit(RRU), a radio header (RH), a remote radio head (RRH), a relay, a lowpower node such as a femto, a pico, and so forth. Yet further examplesof the network device may include multi-standard radio (MSR) radioequipment such as MSR BSs, network controllers such as radio networkcontrollers (RNCs) or base station controllers (BSCs), base transceiverstations (BTSs), transmission points, transmission nodes. Moregenerally, however, the network device may represent any suitable device(or group of devices) capable, configured, arranged, and/or operable toenable and/or provide a terminal device access to the wirelesscommunication network or to provide some service to a terminal devicethat has accessed the wireless communication network.

The term “terminal device” refers to any end device that can access awireless communication network and receive services therefrom. By way ofexample and not limitation, the terminal device refers to a mobileterminal, user equipment (UE), or other suitable devices. The UE may be,for example, a Subscriber Station (SS), a Portable Subscriber Station, aMobile Station (MS), or an Access Terminal (AT). The terminal device mayinclude, but not limited to, portable computers, image capture terminaldevices such as digital cameras, gaming terminal devices, music storageand playback appliances, a mobile phone, a cellular phone, a smartphone, voice over IP (VoIP) phones, wireless local loop phones, atablet, a wearable device, a personal digital assistant (PDA), wearableterminal devices, vehicle-mounted wireless terminal devices, wirelessendpoints, mobile stations, laptop-embedded equipment (LEE),laptop-mounted equipment (LME), USB dongles, smart devices, wirelesscustomer-premises equipment (CPE) and the like. In the followingdescription, the terms “terminal device”, “terminal”, “user equipment”and “UE” may be used interchangeably. As one example, a terminal devicemay represent a UE configured for communication in accordance with oneor more communication standards promulgated by the 3rd GenerationPartnership Project (3GPP), such as 3GPP's GSM, UMTS, LTE, and/or 5Gstandards. As used herein, a “user equipment” or “UE” may notnecessarily have a “user” in the sense of a human user who owns and/oroperates the relevant device. In some embodiments, a terminal device maybe configured to transmit and/or receive information without directhuman interaction. For instance, a terminal device may be designed totransmit information to a network on a predetermined schedule, whentriggered by an internal or external event, or in response to requestsfrom the wireless communication network. Instead, a UE may represent adevice that is intended for sale to, or operation by, a human user butthat may not initially be associated with a specific human user.

The terminal device may support device-to-device (D2D) communication,for example by implementing a 3GPP standard for sidelink communication,and may in this case be referred to as a D2D communication device.

As yet another example, in an Internet of Things (IOT) scenario, aterminal device may represent a machine or other device that performsmonitoring and/or measurements, and transmits the results of suchmonitoring and/or measurements to another terminal device and/or networkequipment. The terminal device may in this case be a machine-to-machine(M2M) device, which may in a 3GPP context be referred to as amachine-type communication (MTC) device. As one particular example, theterminal device may be a UE implementing the 3GPP narrow band internetof things (NB-IoT) standard. Particular examples of such machines ordevices are sensors, metering devices such as power meters, industrialmachinery, or home or personal appliances, for example refrigerators,televisions, personal wearables such as watches etc. In other scenarios,a terminal device may represent a vehicle or other equipment that iscapable of monitoring and/or reporting on its operational status orother functions associated with its operation.

As used herein, a downlink, DL transmission refers to a transmissionfrom the network device to a terminal device, and an uplink, ULtransmission refers to a transmission in an opposite direction.

References in the specification to “one embodiment,” “an embodiment,”“an example embodiment,” and the like indicate that the embodimentdescribed may include a particular feature, structure, orcharacteristic, but it is not necessary that every embodiment includesthe particular feature, structure, or characteristic. Moreover, suchphrases are not necessarily referring to the same embodiment. Further,when a particular feature, structure, or characteristic is described inconnection with an embodiment, it is submitted that it is within theknowledge of one skilled in the art to affect such feature, structure,or characteristic in connection with other embodiments whether or notexplicitly described.

It shall be understood that although the terms “first” and “second” etc.may be used herein to describe various elements, these elements shouldnot be limited by these terms. These terms are only used to distinguishone element from another. For example, a first element could be termed asecond element, and similarly, a second element could be termed a firstelement, without departing from the scope of example embodiments. Asused herein, the term “and/or” includes any and all combinations of oneor more of the associated listed terms.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be liming of exampleembodiments. As used herein, the singular forms “a”, “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises”, “comprising”, “has”, “having”, “includes” and/or“including”, when used herein, specify the presence of stated features,elements, and/or components etc., but do not preclude the presence oraddition of one or more other features, elements, components and/orcombinations thereof.

In the following description and claims, unless defined otherwise, alltechnical and scientific terms used herein have the same meaning ascommonly understood by one of ordinary skills in the art to which thisdisclosure belongs.

In Summary on BFR detection and other BFR issues, 3GPP TSG-RAN WG2 NR Adhoc 0118, R2-1801558, Vancouver, Canada, 22 Jan.-26 Jan. 2018, it hasbeen proposed to initiate a BFR procedure in a PCell to support BFR inan SCell.

When a terminal device detects a beam failure in an SCell, it cantransmit a beam failure report to a network device via a MAC CE overPUSCH in a PCell. The report may indicate one or more candidate beamsfor BFR. Upon receipt of the beam failure report, the network device caninstruct the terminal device to perform PRACH-based procedure using acandidate beam. This may require allocating dedicated PRACH resources inthe PCell for candidate beams for the purpose of BFR, which may resultin PRACH overload in the PCell.

FIG. 1 is a flowchart illustrating a method 100 for configuration of BFRaccording to an embodiment of the present disclosure. The method 100 canbe performed at a network device.

At block 110, the network device receives from a terminal device a beamfailure report associated with an SCell. The beam failure report can bereceived in a PCell.

At block 120, the network device configures the terminal device with atleast one of the following BFR options: BFR with PUCCH, BFR with CFRA,BFR with CBRA, and BFR without PRACH and PUCCH.

In an example, the network device can transmit to the terminal device anacknowledgement of receipt of the beam failure report. Theacknowledgement can be transmitted in the PCell, a PUCCH SCell, or anSCell with a configured downlink.

In this case, in the block 110, the at least one BFR option can beconfigured in the acknowledgement.

Further, the acknowledgement may indicate an index or Cell/CarrierIndicator Flag (CIF) of the SCell where a beam failure occurs asindicated in the beam failure report. Additionally or alternatively, theacknowledgement may indicate an index of a candidate beam recommendedfor BFR. The recommended candidate beam may be selected from a set ofcandidate beams indicated in the beam failure report based on e.g.,their beam radio qualities. For example, the recommended candidate beamcan have a Synchronization Signal-Reference Signal Received Power(SS-RSRP) higher than a predetermined threshold. The network device maynot always select the candidate beam having the highest radio qualityfor load balancing. Additionally or alternatively, the acknowledgementmay indicate an indicator of one of the BFR options. Additionally oralternatively, the acknowledgement may indicate a PUCCH resource whenthe BFR with PUCCH is configured, or a PRACH resource when the BFR withCFRA is configured, for use by the terminal device in the BFR. Thisallows saving PUCCH/PRACH resources when compared with always reservingPUCCH/PRACH resources for BFR.

Additionally or alternatively, the acknowledgement may indicate an indexof a serving cell in which the terminal device is to perform the BFR.For the BFR with PUCCH, BFR with CFRA and BFR with CBRA, the servingcell here can be the PCell, the SCell where the beam failure occurs asindicated in the beam failure report, or any other SCell. For the BFRwithout PRACH and PUCCH, the serving cell here will be the SCell wherethe beam failure occurs. Optionally, when a Supplementary Uplink (SUL)carrier is configured for that serving cell, the acknowledgement mayfurther indicate whether the SUL carrier is to be used for the BFR.

In an example where the BFR with PUCCH is configured, the network devicecan configure the terminal device with a PUCCH resource pool via RadioResource Control (RRC) signaling. Upon receipt of the beam failurereport, the network device can indicate in the acknowledgement a PUCCHresource in the PUCCH resource pool.

In an example, the acknowledgement can be transmitted in a MAC CE. Inthis case, a new MAC CE can be defined, which contains new fields forcarrying the above described information to be indicated by theacknowledgement. Furthermore, the acknowledgement can be transmitted inone single MAC CE along with another acknowledgement of receipt ofanother beam failure report associated with another SCell. For example,when there is more than one beam failure reported by the terminaldevice, the network device can aggregate more than one acknowledgementinto one single MAC CE. In this case, a bitmap field can be included inthe MAC CE for indicating the serving cell or candidate beam for use bythe terminal device in the BFR.

In another example, the acknowledgement can be transmitted via RRCsignaling, instead of MAC CE. An RRC message can be defined to carry theabove-described information to be indicated by the acknowledgement.

Alternatively, in the block 120, the at least one BFR option can beconfigured via RRC signaling. For example, the block 120 may occurbefore the block 110 and the network device can preconfigure theterminal device with one or more BFR options via RRC signaling. In thiscase, optionally, when receiving the beam failure report, the networkdevice can transmit to the terminal device an acknowledgement of receiptof the beam failure report. The acknowledgement may include an index orCIF of the SCell; an index of a candidate beam recommended for BFR; anindicator of one of the BFR options; a PUCCH resource when the BFR withPUCCH is configured, or a PRACH resource when the BFR with CFRA isconfigured; and an index of a serving cell in which the terminal deviceis to perform the BFR, and/or when a SUL carrier is configured for thatserving cell, an indication of whether the SUL carrier is to be used forthe BFR, as described above. Alternatively, the acknowledgement can betransmitted as a special MAC CE that is identified by a MAC ProtocolData Unit (PDU) sub-header with a predefined Logic Channel Identifier(LCID) and has a null payload. Upon receipt of such special MAC CE, theterminal device can perform a BFR in accordance with the preconfiguredBFR option (when more than one BFR option is configured, the terminaldevice can select one of the BFR options as appropriate). As anotheralternative, the network device does not transmit any acknowledgement tothe terminal device. In this case, the terminal device can also performa BFR in accordance with the preconfigured BFR option (when more thanone BFR option is configured, the terminal device can select one of theBFR options as appropriate). In an example, when no acknowledgement isavailable, the terminal device can perform a BFR without PRACH andPUCCH.

In an example, the network device can configure the terminal device witha BFR priority for each serving cell (particularly each SCell), e.g.,via RRC signaling. When beam failures occur in more than one servingcell, a serving cell having a higher BFR priority will have its beamfailure reported earlier and its associated BFR triggered earlier. TheBFR priority of a serving cell can be configured based on at least oneof: a carrier frequency of that serving cell (e.g., a serving cellhaving a higher carrier frequency may have a higher BFR priority), anumerology or transmission duration of that serving cell (e.g., aserving cell having a larger Sub-Carrier Spacing (SCS) and/or smallertransmission duration may have a higher BFR priority), a service orlogical channel associated with or mapped to that serving cell (e.g., aserving cell having a service or logical channel associated with higherQuality of Service (QoS) may have a higher BFR priority), a traffic loadin that serving cell (e.g., a serving cell having a higher traffic loadmay have a higher BFR priority) and whether the serving cell is a PUCCHSCell (e.g., a PUCCH SCell may have a higher BFR priority than anon-PUCCH SCell).

FIG. 2 is a flowchart illustrating a method 200 for BFR according to anembodiment of the present disclosure. The method 200 can be performed ata terminal device.

At block 210, the terminal device detects a beam failure associated withan SCell.

At block 220, the network device transmits to a network device a beamfailure report associated with the beam failure. The beam failure reportcan be transmitted in a PCell.

At block 230, the terminal device receives a configuration of at leastone of the following BFR options: BFR with PUCCH, BFR with CFRA, BFRwith CBRA, and BFR without PRACH and PUCCH.

At block 240, the terminal device performs a BFR in accordance with theat least one BFR option. Here, when more than one BFR option isconfigured, the terminal device can select one of the configured BFRoptions as appropriate for performing the BFR.

In an example, after transmitting the beam failure report to the networkdevice, the terminal device can receive from the network device anacknowledgement of receipt of the beam failure report. Theacknowledgement can be received in the PCell, a PUCCH SCell, or an SCellwith a configured downlink.

In this case, in the block 230, the configuration of the at least oneBFR option can be received in the acknowledgement.

Further, as described above in connection with the method 100, theacknowledgement can indicate one or more of: an index or CIF of theSCell; an index of a candidate beam recommended for BFR; an indicator ofone of the BFR options; a PUCCH resource when the BFR with PUCCH isconfigured, or a PRACH resource when the BFR with CFRA is configured;and an index of a serving cell in which the terminal device is toperform the BFR, and/or when a SUL carrier is configured for thatserving cell, an indication of whether the SUL carrier is to be used forthe BFR.

In an example where the BFR with PUCCH is configured, the terminaldevice can receive from the network device a configuration of a PUCCHresource pool via RRC signaling. In this case, the acknowledgement canindicate a PUCCH resource in the PUCCH resource pool.

In an example, the acknowledgement can be received in a MAC CE. Asdescribed above in connection with the method 100, a new MAC CE can bedefined, which contains new fields for carrying the above describedinformation to be indicated by the acknowledgement. Furthermore, theacknowledgement can be received in one single MAC CE along with anotheracknowledgement of receipt of another beam failure report associatedwith another SCell. In this case, a bitmap field can be included in theMAC CE for indicating the serving cell or candidate beam for use by theterminal device in the BFR.

In another example, the acknowledgement can be received via RRCsignaling, instead of MAC CE. An RRC message can be defined to carry theabove-described information to be indicated by the acknowledgement.

Alternatively, in the block 230, the configuration of the at least oneBFR option can be received via RRC signaling. For example, the block 230may occur before the block 210 and the terminal device can bepreconfigured with one or more BFR options via RRC signaling. In thiscase, optionally, the terminal device can receive from the networkdevice an acknowledgement of receipt of the beam failure report. Theacknowledgement may include an index or CIF of the SCell; an index of acandidate beam recommended for BFR; an indicator of one of the BFRoptions; a PUCCH resource when the BFR with PUCCH is configured, or aPRACH resource when the BFR with CFRA is configured; and an index of aserving cell in which the terminal device is to perform the BFR, and/orwhen a SUL carrier is configured for that serving cell, an indication ofwhether the SUL carrier is to be used for the BFR, as described above.Alternatively, the acknowledgement can be received as a special MAC CEthat is identified by a MAC PDU sub-header with a predefined LCID andhas a null payload. Upon receipt of such special MAC CE, the terminaldevice can perform a BFR in accordance with the preconfigured BFR option(when more than one BFR option is configured, the terminal device canselect one of the BFR options as appropriate). As another alternative,no acknowledgement is received by the terminal device. In this case, theterminal device can also perform a BFR in accordance with thepreconfigured BFR option (when more than one BFR option is configured,the terminal device can select one of the BFR options as appropriate).In an example, when no acknowledgement is available, the terminal devicecan perform a BFR without PRACH and PUCCH.

In an example, when the BFR is performed in accordance with the BFRwithout PRACH and PUCCH, in the block 240, the BFR can be performed inthe SCell. In this case, the terminal device can determine whether theBFR has succeeded based on a downlink data transmission in the SCell. Inparticular, the terminal device can receive a downlink data over aPhysical Downlink Shared Channel (PDSCH) and then transmit a HybridAutomatic Repeat reQuest (HARQ) Acknowledgement (ACK) orNon-Acknowledgement (NACK) over PUCCH in response to the downlink data.When an ACK is transmitted, the terminal device can determine that theBFR has succeeded when no further Physical Downlink Control Channel(PDCCH) is received for scheduling retransmission of the downlink data.On the other hand, when a NACK is transmitted, the terminal device candetermine that the BFR has succeeded when Downlink Control Information(DCI) is received for scheduling retransmission of the downlink datawith a redundancy version value different from an initial value orwithout New Data Indication (NDI) toggling.

Alternatively, the terminal device can determine whether the BFR hassucceeded based on an uplink data transmission in the SCell. Inparticular, the terminal device can transmit an uplink data over aPhysical Uplink Shared Channel (PUSCH). Then, the terminal device candetermine that the BFR has succeeded when no DCI is received forscheduling retransmission of the uplink data within a predetermined timeperiod, or when DCI is received for scheduling retransmission of theuplink data with a redundancy version value different from an initialvalue or without NDI toggling.

In an example, the terminal device can receive from the network device aconfiguration of a BFR priority for each serving cell (particularly eachSCell), e.g., via RRC signaling. When beam failures occur in more thanone serving cell, a serving cell having a higher BFR priority will haveits beam failure reported earlier and its associated BFR triggeredearlier. The BFR priority of a serving cell can be dependent on at leastone of: a carrier frequency of that serving cell (e.g., a serving cellhaving a higher carrier frequency may have a higher BFR priority), anumerology or transmission duration of that serving cell (e.g., aserving cell having a larger Sub-Carrier Spacing (SCS) and/or smallertransmission duration may have a higher BFR priority), a service orlogical channel associated with or mapped to that serving cell (e.g., aserving cell having a service or logical channel associated with higherQuality of Service (QoS) may have a higher BFR priority), a traffic loadin that serving cell (e.g., a serving cell having a higher traffic loadmay have a higher BFR priority) and whether the serving cell is a PUCCHSCell (e.g., a PUCCH SCell may have a higher BFR priority than anon-PUCCH SCell).

In an example, when the beam failure is detected in the block 210 andthere is no uplink grant available for the beam failure report, theterminal device can transmit to the network device a PUCCH SchedulingRequest (SR) for requesting an uplink grant for transmission of the beamfailure report. Conventionally, a PUCCH SR can only be triggered for aBuffer Status Report (BSR) indicating new data arrival at the terminaldevice. A new rule can be defined such that a PUCCH SR can be triggeredwhen the terminal device has a beam failure report for transmission.

In an example, when the beam failure report is transmitted in the block220, a timer associated with an acknowledgement (referred to asretxBFReport-Timer) can be started. If an acknowledgement is receivedbefore expiry of the timer, the timer will be reset; otherwise theterminal device can retransmit the beam failure report upon expiry ofthe timer.

Correspondingly to the method 100 as described above, a network deviceis provided. FIG. 3 is a block diagram of a network device 300 accordingto an embodiment of the present disclosure.

As shown in FIG. 3 , the network device 300 includes a receiving unit310 configured to receive from a terminal device a beam failure reportassociated with an SCell. The network device 300 further includes aconfiguring unit 320 configured to configure the terminal device with atleast one of the following BFR options: BFR with Physical Uplink ControlChannel (PUCCH), BFR with Contention Free Random Access (CFRA), BFR withContention Based Random Access (CBRA), and BFR without Physical RandomAccess Channel (PRACH) and PUCCH.

In an embodiment, the network device 300 can further include atransmitting unit configured to transmit to the terminal device anacknowledgement of receipt of the beam failure report.

In an embodiment, the at least one BFR option can be configured in theacknowledgement.

In an embodiment, the acknowledgement can indicate one or more of: anindex or Cell/Carrier Indicator Flag (CIF) of the SCell, an index of acandidate beam recommended for BFR, an indicator of one of the BFRoptions; a PUCCH resource when the BFR with PUCCH is configured, or aPRACH resource when the BFR with CFRA is configured, and an index of aserving cell in which the terminal device is to perform the BFR, and/orwhen a Supplementary Uplink (SUL) carrier is configured for that servingcell, an indication of whether the SUL carrier is to be used for theBFR.

In an embodiment, the configuring unit 320 can be further configured toconfigure the terminal device with a PUCCH resource pool via RadioResource Control (RRC) signaling. The acknowledgement can indicate aPUCCH resource in the PUCCH resource pool.

In an embodiment, the acknowledgement can be transmitted in a MediumAccess Control (MAC) Control Element (CE).

In an embodiment, the acknowledgement can be transmitted in one singleMAC CE along with another acknowledgement of receipt of another beamfailure report associated with another SCell.

In an embodiment, the acknowledgement can be transmitted via RRCsignaling.

In an embodiment, the acknowledgement can be transmitted as a MAC CEthat is identified by a MAC Protocol Data Unit (PDU) sub-header with apredefined Logic Channel Identifier (LCID) and has a null payload.

In an embodiment, the at least one BFR option can be configured via RRCsignaling.

In an embodiment, the acknowledgement can be transmitted in a PrimaryCell (PCell), a PUCCH SCell, or an SCell with a configured downlink.

In an embodiment, the configuring unit 320 can be further configured toconfigure the terminal device with a BFR priority for each serving cellbased on at least one of: a carrier frequency of that serving cell, anumerology or transmission duration of that serving cell, a service orlogical channel associated with or mapped to that serving cell, atraffic load in that serving cell and whether the serving cell is aPUCCH SCell.

The receiving unit 310 and the configuring unit 320 can be configured tocan be implemented as a pure hardware solution or as a combination ofsoftware and hardware, e.g., by one or more of: a processor or amicro-processor and adequate software and memory for storing of thesoftware, a Programmable Logic Device (PLD) or other electroniccomponent(s) or processing circuitry configured to perform the actionsdescribed above, and illustrated, e.g., in FIG. 1 .

FIG. 4 is a block diagram of a network device 400 according to anotherembodiment of the present disclosure.

The network device 400 includes a transceiver 410, a processor 420 and amemory 430. The memory 430 contains instructions executable by theprocessor 420 whereby the network device 400 is operative to perform theactions, e.g., of the procedure described earlier in conjunction withFIG. 1 . Particularly, the memory 430 contains instructions executableby the processor 420 whereby the network device 400 is operative to:receive from a terminal device a beam failure report associated with anSCell; and configure the terminal device with at least one of thefollowing BFR options: BFR with Physical Uplink Control Channel (PUCCH),BFR with Contention Free Random Access (CFRA), BFR with Contention BasedRandom Access (CBRA), and BFR without Physical Random Access Channel(PRACH) and PUCCH.

In an embodiment, the memory 430 can further contain instructionsexecutable by the processor 420 whereby the network device 400 isoperative to transmit to the terminal device an acknowledgement ofreceipt of the beam failure report.

In an embodiment, the at least one BFR option can be configured in theacknowledgement.

In an embodiment, the acknowledgement can indicate one or more of: anindex or Cell/Carrier Indicator Flag (CIF) of the SCell, an index of acandidate beam recommended for BFR, an indicator of one of the BFRoptions; a PUCCH resource when the BFR with PUCCH is configured, or aPRACH resource when the BFR with CFRA is configured, and an index of aserving cell in which the terminal device is to perform the BFR, and/orwhen a Supplementary Uplink (SUL) carrier is configured for that servingcell, an indication of whether the SUL carrier is to be used for theBFR.

In an embodiment, the memory 430 can further contain instructionsexecutable by the processor 420 whereby the network device 400 isoperative to configure the terminal device with a PUCCH resource poolvia Radio Resource Control (RRC) signaling. The acknowledgement canindicate a PUCCH resource in the PUCCH resource pool.

In an embodiment, the acknowledgement can be transmitted in a MediumAccess Control (MAC) Control Element (CE).

In an embodiment, the acknowledgement can be transmitted in one singleMAC CE along with another acknowledgement of receipt of another beamfailure report associated with another SCell.

In an embodiment, the acknowledgement can be transmitted via RRCsignaling.

In an embodiment, the acknowledgement can be transmitted as a MAC CEthat is identified by a MAC Protocol Data Unit (PDU) sub-header with apredefined Logic Channel Identifier (LCID) and has a null payload.

In an embodiment, the at least one BFR option can be configured via RRCsignaling.

In an embodiment, the acknowledgement can be transmitted in a PrimaryCell (PCell), a PUCCH SCell, or an SCell with a configured downlink.

In an embodiment, the memory 430 can further contain instructionsexecutable by the processor 420 whereby the network device 400 isoperative to configure the terminal device with a BFR priority for eachserving cell based on at least one of: a carrier frequency of thatserving cell, a numerology or transmission duration of that servingcell, a service or logical channel associated with or mapped to thatserving cell, a traffic load in that serving cell and whether theserving cell is a PUCCH SCell.

Correspondingly to the method 200 as described above, a terminal deviceis provided. FIG. 5 is a block diagram of a terminal device 500according to an embodiment of the present disclosure.

As shown in FIG. 5 , the terminal device 500 includes a detecting unit510 configured to detect a beam failure associated with a Secondary Cell(SCell). The terminal device 500 further includes a transmitting unit520 configured to transmit to a network device a beam failure reportassociated with the beam failure. The terminal device 500 furtherincludes a receiving unit 530 configured to receive a configuration ofat least one of the following BFR options: BFR with Physical UplinkControl Channel (PUCCH), BFR with Contention Free Random Access (CFRA),BFR with Contention Based Random Access (CBRA), and BFR without PhysicalRandom Access Channel (PRACH) and PUCCH. The terminal device 500 furtherincludes a BFR unit 540 configured to perform a BFR in accordance withthe at least one BFR option.

In an embodiment, the receiving unit 530 can further be configured toreceive from the network device an acknowledgement of receipt of thebeam failure report.

In an embodiment, the configuration of the at least one BFR option canbe received in the acknowledgement.

In an embodiment, the acknowledgement can indicate one or more of: anindex or Cell/Carrier Indicator Flag (CIF) of the SCell, an index of acandidate beam recommended for BFR, an indicator of one of the BFRoptions; a PUCCH resource when the BFR with PUCCH is configured, or aPRACH resource when the BFR with CFRA is configured, and an index of aserving cell in which the terminal device is to perform the BFR, and/orwhen a Supplementary Uplink (SUL) carrier is configured for that servingcell, an indication of whether the SUL carrier is to be used for theBFR.

In an embodiment, the receiving unit 530 can further be configured toreceive from the network device a configuration of a PUCCH resource poolvia Radio Resource Control (RRC) signaling. The acknowledgement canindicate a PUCCH resource in the PUCCH resource pool.

In an embodiment, the acknowledgement can be received in a Medium AccessControl, (MAC) Control Element (CE).

In an embodiment, the acknowledgement can be received in one single MACCE along with another acknowledgement of receipt of another beam failurereport associated with another SCell.

In an embodiment, the acknowledgement can be received via RRC signaling.

In an embodiment, the acknowledgement can be received as a MAC CE thatis identified by a MAC Protocol Data Unit (PDU) sub-header with apredefined Logic Channel Identifier (LCID) and has a null payload.

In an embodiment, the configuration of the at least one BFR option canbe received via RRC signaling.

In an embodiment, the acknowledgement can be received in a Primary Cell(PCell), a PUCCH SCell, or an SCell with a configured downlink.

In an embodiment, when the BFR is performed in accordance with the BFRwithout PRACH and PUCCH, the BFR can be performed in the SCell. The BFRunit 540 can be further configured to: determine whether the BFR hassucceeded based on a downlink or uplink data transmission in the SCell.

In an embodiment, the BFR unit 540 can be configured to determinewhether the BFR has succeeded based on a downlink data transmission inthe SCell by: receiving a downlink data over a Physical Downlink SharedChannel (PDSCH); transmitting a Hybrid Automatic Repeat reQuest (HARQ)Acknowledgement (ACK) or Non-Acknowledgement (NACK) over PUCCH inresponse to the downlink data; and determining, when an ACK istransmitted, that the BFR has succeeded when no further PhysicalDownlink Control Channel (PDCCH) is received for schedulingretransmission of the downlink data, or determining, when a NACK istransmitted, that the BFR has succeeded when Downlink ControlInformation (DCI) is received for scheduling retransmission of thedownlink data with a redundancy version value different from an initialvalue or without New Data Indication (NDI) toggling.

In an embodiment, the BFR unit 540 can be configured to determinewhether the BFR has succeeded based on an uplink data transmission inthe SCell by: transmitting an uplink data over a Physical Uplink SharedChannel (PUSCH); and determining that the BFR has succeeded when noDownlink Control Information (DCI) is received for schedulingretransmission of the uplink data within a predetermined time period, orDCI is received for scheduling retransmission of the uplink data with aredundancy version value different from an initial value or without NewData Indication (NDI) toggling.

In an embodiment, the receiving unit 530 can further be configured toreceive from the network device a configuration of a BFR priority foreach serving cell dependent on at least one of: a carrier frequency ofthat serving cell, a numerology or transmission duration of that servingcell, a service or logical channel associated with or mapped to thatserving cell, a traffic load in that serving cell and whether theserving cell is a PUCCH SCell.

In an embodiment, the transmitting unit 520 can further be configuredto, prior to transmitting the beam failure report: transmit to thenetwork device a PUCCH Scheduling Request (SR) for requesting an uplinkgrant for transmission of the beam failure report.

In an embodiment, the transmitting unit 520 can further be configured tostart a timer associated with the acknowledgement when the beam failurereport is transmitted; and retransmit the beam failure report uponexpiry of the timer.

The detecting unit 510, the transmitting unit 520, the receiving unit530 and the BFR unit 540 can be implemented as a pure hardware solutionor as a combination of software and hardware, e.g., by one or more of: aprocessor or a micro-processor and adequate software and memory forstoring of the software, a Programmable Logic Device (PLD) or otherelectronic component(s) or processing circuitry configured to performthe actions described above, and illustrated, e.g., in FIG. 2 .

FIG. 6 is a block diagram of a terminal device 600 according to anotherembodiment of the present disclosure.

The terminal device 600 includes a transceiver 610, a processor 620 anda memory 630. The memory 630 contains instructions executable by theprocessor 620 whereby the terminal device 600 is operative to performthe actions, e.g., of the procedure described earlier in conjunctionwith FIG. 2 . Particularly, the memory 630 contains instructionsexecutable by the processor 620 whereby the terminal device 600 isoperative to: detect a beam failure associated with a Secondary Cell(SCell); and transmit to a network device a beam failure reportassociated with the beam failure. The memory 630 further containsinstructions executable by the processor 620 whereby the terminal device600 is operative to: receive a configuration of at least one of thefollowing BFR options: BFR with Physical Uplink Control Channel (PUCCH),BFR with Contention Free Random Access (CFRA), BFR with Contention BasedRandom Access (CBRA), and BFR without Physical Random Access Channel(PRACH) and PUCCH; and perform a BFR in accordance with the at least oneBFR option.

In an embodiment, the memory 630 can further contain instructionsexecutable by the processor 620 whereby the terminal device 600 isoperative to: receive from the network device an acknowledgement ofreceipt of the beam failure report.

In an embodiment, the configuration of the at least one BFR option canbe received in the acknowledgement.

In an embodiment, the acknowledgement can indicate one or more of: anindex or Cell/Carrier Indicator Flag (CIF) of the SCell, an index of acandidate beam recommended for BFR, an indicator of one of the BFRoptions; a PUCCH resource when the BFR with PUCCH is configured, or aPRACH resource when the BFR with CFRA is configured, and an index of aserving cell in which the terminal device is to perform the BFR, and/orwhen a Supplementary Uplink (SUL) carrier is configured for that servingcell, an indication of whether the SUL carrier is to be used for theBFR.

In an embodiment, the memory 630 can further contain instructionsexecutable by the processor 620 whereby the terminal device 600 isoperative to receive from the network device a configuration of a PUCCHresource pool via Radio Resource Control (RRC) signaling. Theacknowledgement can indicate a PUCCH resource in the PUCCH resourcepool.

In an embodiment, the acknowledgement can be received in a Medium AccessControl, (MAC) Control Element (CE).

In an embodiment, the acknowledgement can be received in one single MACCE along with another acknowledgement of receipt of another beam failurereport associated with another SCell.

In an embodiment, the acknowledgement can be received via RRC signaling.

In an embodiment, the acknowledgement can be received as a MAC CE thatis identified by a MAC Protocol Data Unit (PDU) sub-header with apredefined Logic Channel Identifier (LCID) and has a null payload.

In an embodiment, the configuration of the at least one BFR option canbe received via RRC signaling.

In an embodiment, the acknowledgement can be received in a Primary Cell(PCell), a PUCCH SCell, or an SCell with a configured downlink.

In an embodiment, when the BFR is performed in accordance with the BFRwithout PRACH and PUCCH, the BFR can be performed in the SCell. Thememory 630 can further contain instructions executable by the processor620 whereby the terminal device 600 is operative to determine whetherthe BFR has succeeded based on a downlink or uplink data transmission inthe SCell.

In an embodiment, the operation of determining whether the BFR hassucceeded based on a downlink data transmission in the SCell caninclude: receiving a downlink data over a Physical Downlink SharedChannel (PDSCH); transmitting a Hybrid Automatic Repeat reQuest (HARQ)Acknowledgement (ACK) or Non-Acknowledgement (NACK) over PUCCH inresponse to the downlink data; and determining, when an ACK istransmitted, that the BFR has succeeded when no further PhysicalDownlink Control Channel (PDCCH) is received for schedulingretransmission of the downlink data, or determining, when a NACK istransmitted, that the BFR has succeeded when Downlink ControlInformation (DCI) is received for scheduling retransmission of thedownlink data with a redundancy version value different from an initialvalue or without New Data Indication (NDI) toggling.

In an embodiment, the operation of determining whether the BFR hassucceeded based on an uplink data transmission in the SCell can include:transmitting an uplink data over a Physical Uplink Shared Channel(PUSCH); and determining that the BFR has succeeded when no DownlinkControl Information (DCI) is received for scheduling retransmission ofthe uplink data within a predetermined time period, or DCI is receivedfor scheduling retransmission of the uplink data with a redundancyversion value different from an initial value or without New DataIndication (NDI) toggling.

In an embodiment, the memory 630 can further contain instructionsexecutable by the processor 620 whereby the terminal device 600 isoperative to receive from the network device a configuration of a BFRpriority for each serving cell dependent on at least one of: a carrierfrequency of that serving cell, a numerology or transmission duration ofthat serving cell, a service or logical channel associated with ormapped to that serving cell, a traffic load in that serving cell andwhether the serving cell is a PUCCH SCell.

In an embodiment, the memory 630 can further contain instructionsexecutable by the processor 620 whereby the terminal device 600 isoperative to, prior to transmitting the beam failure report: transmit tothe network device a PUCCH Scheduling Request (SR) for requesting anuplink grant for transmission of the beam failure report.

In an embodiment, the memory 630 can further contain instructionsexecutable by the processor 620 whereby the terminal device 600 isoperative to start a timer associated with the acknowledgement when thebeam failure report is transmitted; and retransmit the beam failurereport upon expiry of the timer.

The present disclosure also provides at least one computer programproduct in the form of a non-volatile or volatile memory, e.g., anon-transitory computer readable storage medium, an ElectricallyErasable Programmable Read-Only Memory (EEPROM), a flash memory and ahard drive. The computer program product includes a computer program.The computer program includes: code/computer readable instructions,which when executed by the processor 420 causes the network device 400to perform the actions, e.g., of the procedure described earlier inconjunction with FIG. 1 ; or code/computer readable instructions, whichwhen executed by the processor 620 causes the terminal device 600 toperform the actions, e.g., of the procedure described earlier inconjunction with FIG. 2 .

The computer program product may be configured as a computer programcode structured in computer program modules. The computer programmodules could essentially perform the actions of the flow illustrated inFIG. 1 or 2 .

The processor may be a single CPU (Central processing unit), but couldalso comprise two or more processing units. For example, the processormay include general purpose microprocessors; instruction set processorsand/or related chips sets and/or special purpose microprocessors such asApplication Specific Integrated Circuit (ASICs). The processor may alsocomprise board memory for caching purposes. The computer program may becarried by a computer program product connected to the processor. Thecomputer program product may comprise a non-transitory computer readablestorage medium on which the computer program is stored. For example, thecomputer program product may be a flash memory, a Random-access memory(RAM), a Read-Only Memory (ROM), or an EEPROM, and the computer programmodules described above could in alternative embodiments be distributedon different computer program products in the form of memories.

With reference to FIG. 7 , in accordance with an embodiment, acommunication system includes a telecommunication network 710, such as a3GPP-type cellular network, which comprises an access network 711, suchas a radio access network, and a core network 714. The access network711 comprises a plurality of base stations 712 a, 712 b, 712 c, such asNBs, eNBs, gNBs or other types of wireless access points, each defininga corresponding coverage area 713 a, 713 b, 713 c. Each base station 712a, 712 b, 712 c is connectable to the core network 714 over a wired orwireless connection 715. A first user equipment (UE) 771 located incoverage area 713 c is configured to wirelessly connect to, or be pagedby, the corresponding base station 712 c. A second UE 772 in coveragearea 713 a is wirelessly connectable to the corresponding base station712 a. While a plurality of UEs 771, 772 are illustrated in thisexample, the disclosed embodiments are equally applicable to a situationwhere a sole UE is in the coverage area or where a sole UE is connectingto the corresponding base station 712.

The telecommunication network 710 is itself connected to a host computer730, which may be embodied in the hardware and/or software of astandalone server, a cloud-implemented server, a distributed server oras processing resources in a server farm. The host computer 730 may beunder the ownership or control of a service provider, or may be operatedby the service provider or on behalf of the service provider. Theconnections 721, 722 between the telecommunication network 710 and thehost computer 730 may extend directly from the core network 714 to thehost computer 730 or may go via an optional intermediate network 720.The intermediate network 720 may be one of, or a combination of morethan one of, a public, private or hosted network; the intermediatenetwork 720, if any, may be a backbone network or the Internet; inparticular, the intermediate network 720 may comprise two or moresub-networks (not shown).

The communication system of FIG. 7 as a whole enables connectivitybetween one of the connected UEs 771, 772 and the host computer 730. Theconnectivity may be described as an over-the-top (OTT) connection 750.The host computer 730 and the connected UEs 771, 772 are configured tocommunicate data and/or signaling via the OTT connection 750, using theaccess network 711, the core network 714, any intermediate network 720and possible further infrastructure (not shown) as intermediaries. TheOTT connection 750 may be transparent in the sense that theparticipating communication devices through which the OTT connection 750passes are unaware of routing of uplink and downlink communications. Forexample, a base station 712 may not or need not be informed about thepast routing of an incoming downlink communication with data originatingfrom a host computer 730 to be forwarded (e.g., handed over) to aconnected UE 771. Similarly, the base station 712 need not be aware ofthe future routing of an outgoing uplink communication originating fromthe UE 771 towards the host computer 730.

Example implementations, in accordance with an embodiment, of the UE,base station and host computer discussed in the preceding paragraphswill now be described with reference to FIG. 8 . In a communicationsystem 800, a host computer 810 comprises hardware 815 including acommunication interface 816 configured to set up and maintain a wired orwireless connection with an interface of a different communicationdevice of the communication system 800. The host computer 810 furthercomprises processing circuitry 818, which may have storage and/orprocessing capabilities. In particular, the processing circuitry 818 maycomprise one or more programmable processors, application-specificintegrated circuits, field programmable gate arrays or combinations ofthese (not shown) adapted to execute instructions. The host computer 810further comprises software 811, which is stored in or accessible by thehost computer 810 and executable by the processing circuitry 818. Thesoftware 811 includes a host application 812. The host application 812may be operable to provide a service to a remote user, such as a UE 830connecting via an OTT connection 850 terminating at the UE 830 and thehost computer 810. In providing the service to the remote user, the hostapplication 812 may provide user data which is transmitted using the OTTconnection 850.

The communication system 800 further includes a base station 820provided in a telecommunication system and comprising hardware 825enabling it to communicate with the host computer 810 and with the UE830. The hardware 825 may include a communication interface 826 forsetting up and maintaining a wired or wireless connection with aninterface of a different communication device of the communicationsystem 800, as well as a radio interface 827 for setting up andmaintaining at least a wireless connection 870 with a UE 830 located ina coverage area (not shown in FIG. 8 ) served by the base station 820.The communication interface 826 may be configured to facilitate aconnection 860 to the host computer 810. The connection 860 may bedirect or it may pass through a core network (not shown in FIG. 8 ) ofthe telecommunication system and/or through one or more intermediatenetworks outside the telecommunication system. In the embodiment shown,the hardware 825 of the base station 820 further includes processingcircuitry 828, which may comprise one or more programmable processors,application-specific integrated circuits, field programmable gate arraysor combinations of these (not shown) adapted to execute instructions.The base station 820 further has software 821 stored internally oraccessible via an external connection.

The communication system 800 further includes the UE 830 alreadyreferred to. Its hardware 835 may include a radio interface 837configured to set up and maintain a wireless connection 870 with a basestation serving a coverage area in which the UE 830 is currentlylocated. The hardware 835 of the UE 830 further includes processingcircuitry 838, which may comprise one or more programmable processors,application-specific integrated circuits, field programmable gate arraysor combinations of these (not shown) adapted to execute instructions.The UE 830 further comprises software 831, which is stored in oraccessible by the UE 830 and executable by the processing circuitry 838.The software 831 includes a client application 832. The clientapplication 832 may be operable to provide a service to a human ornon-human user via the UE 830, with the support of the host computer810. In the host computer 810, an executing host application 812 maycommunicate with the executing client application 832 via the OTTconnection 850 terminating at the UE 830 and the host computer 810. Inproviding the service to the user, the client application 832 mayreceive request data from the host application 812 and provide user datain response to the request data. The OTT connection 850 may transferboth the request data and the user data. The client application 832 mayinteract with the user to generate the user data that it provides.

It is noted that the host computer 810, base station 820 and UE 830illustrated in FIG. 8 may be identical to the host computer 730, one ofthe base stations 712 a, 712 b, 712 c and one of the UEs 771, 772 ofFIG. 7 , respectively. This is to say, the inner workings of theseentities may be as shown in FIG. 8 and independently, the surroundingnetwork topology may be that of FIG. 7 .

In FIG. 8 , the OTT connection 850 has been drawn abstractly toillustrate the communication between the host computer 810 and the useequipment 830 via the base station 820, without explicit reference toany intermediary devices and the precise routing of messages via thesedevices. Network infrastructure may determine the routing, which it maybe configured to hide from the UE 830 or from the service provideroperating the host computer 810, or both. While the OTT connection 850is active, the network infrastructure may further take decisions bywhich it dynamically changes the routing (e.g., on the basis of loadbalancing consideration or reconfiguration of the network).

The wireless connection 870 between the UE 830 and the base station 820is in accordance with the teachings of the embodiments describedthroughout this disclosure. One or more of the various embodimentsimprove the performance of OTT services provided to the UE 830 using theOTT connection 850, in which the wireless connection 870 forms the lastsegment. More precisely, the teachings of these embodiments may improvePRACH resource utilization and thereby provide benefits such as reduceduser waiting time.

A measurement procedure may be provided for the purpose of monitoringdata rate, latency and other factors on which the one or moreembodiments improve. There may further be an optional networkfunctionality for reconfiguring the OTT connection 850 between the hostcomputer 810 and UE 830, in response to variations in the measurementresults. The measurement procedure and/or the network functionality forreconfiguring the OTT connection 850 may be implemented in the software811 of the host computer 810 or in the software 831 of the UE 830, orboth. In embodiments, sensors (not shown) may be deployed in or inassociation with communication devices through which the OTT connection850 passes; the sensors may participate in the measurement procedure bysupplying values of the monitored quantities exemplified above, orsupplying values of other physical quantities from which software 811,831 may compute or estimate the monitored quantities. The reconfiguringof the OTT connection 850 may include message format, retransmissionsettings, preferred routing etc.; the reconfiguring need not affect thebase station 820, and it may be unknown or imperceptible to the basestation 820. Such procedures and functionalities may be known andpracticed in the art. In certain embodiments, measurements may involveproprietary UE signaling facilitating the host computer's 810measurements of throughput, propagation times, latency and the like. Themeasurements may be implemented in that the software 811, 831 causesmessages to be transmitted, in particular empty or ‘dummy’ messages,using the OTT connection 850 while it monitors propagation times, errorsetc.

FIG. 9 is a flowchart illustrating a method implemented in acommunication system, in accordance with one embodiment. Thecommunication system includes a host computer, a base station and a UEwhich may be those described with reference to FIGS. 7 and 8 . Forsimplicity of the present disclosure, only drawing references to FIG. 9will be included in this section. In a first step 910 of the method, thehost computer provides user data. In an optional substep 911 of thefirst step 910, the host computer provides the user data by executing ahost application. In a second step 920, the host computer initiates atransmission carrying the user data to the UE. In an optional third step930, the base station transmits to the UE the user data which wascarried in the transmission that the host computer initiated, inaccordance with the teachings of the embodiments described throughoutthis disclosure. In an optional fourth step 940, the UE executes aclient application associated with the host application executed by thehost computer.

FIG. 10 is a flowchart illustrating a method implemented in acommunication system, in accordance with one embodiment. Thecommunication system includes a host computer, a base station and a UEwhich may be those described with reference to FIGS. 7 and 8 . Forsimplicity of the present disclosure, only drawing references to FIG. 10will be included in this section. In a first step 1010 of the method,the host computer provides user data. In an optional substep (not shown)the host computer provides the user data by executing a hostapplication. In a second step 1020, the host computer initiates atransmission carrying the user data to the UE. The transmission may passvia the base station, in accordance with the teachings of theembodiments described throughout this disclosure. In an optional thirdstep 1030, the UE receives the user data carried in the transmission.

FIG. 11 is a flowchart illustrating a method implemented in acommunication system, in accordance with one embodiment. Thecommunication system includes a host computer, a base station and a UEwhich may be those described with reference to FIGS. 7 and 8 . Forsimplicity of the present disclosure, only drawing references to FIG. 11will be included in this section. In an optional first step 1110 of themethod, the UE receives input data provided by the host computer.Additionally or alternatively, in an optional second step 1120, the UEprovides user data. In an optional substep 1121 of the second step 1120,the UE provides the user data by executing a client application. In afurther optional substep 1111 of the first step 1110, the UE executes aclient application which provides the user data in reaction to thereceived input data provided by the host computer. In providing the userdata, the executed client application may further consider user inputreceived from the user. Regardless of the specific manner in which theuser data was provided, the UE initiates, in an optional third substep1130, transmission of the user data to the host computer. In a fourthstep 1140 of the method, the host computer receives the user datatransmitted from the UE, in accordance with the teachings of theembodiments described throughout this disclosure.

FIG. 12 is a flowchart illustrating a method implemented in acommunication system, in accordance with one embodiment. Thecommunication system includes a host computer, a base station and a UEwhich may be those described with reference to FIGS. 7 and 8 . Forsimplicity of the present disclosure, only drawing references to FIG. 12will be included in this section. In an optional first step 1210 of themethod, in accordance with the teachings of the embodiments describedthroughout this disclosure, the base station receives user data from theUE. In an optional second step 1220, the base station initiatestransmission of the received user data to the host computer. In a thirdstep 1230, the host computer receives the user data carried in thetransmission initiated by the base station.

The disclosure has been described above with reference to embodimentsthereof. It should be understood that various modifications,alternations and additions can be made by those skilled in the artwithout departing from the spirits and scope of the disclosure.Therefore, the scope of the disclosure is not limited to the aboveparticular embodiments but only defined by the claims as attached.

1. A method in a network device for configuration of Beam FailureRecovery, BFR, comprising: receiving from a terminal device a beamfailure report associated with a Secondary Cell (SCell); and afterreceiving the beam failure report transmitted by the terminal device,transmitting to the terminal device a message comprising at least afirst BFR option indicator indicating one of the following BFR options:BFR with Physical Uplink Control Channel (PUCCH); BFR with ContentionFree Random Access (CFRA); BFR with Contention Based Random Access(CBRA); or BFR without Physical Random Access Channel (PRACH) and PUCCH.2. The method of claim 1, wherein the message comprising the first BFRoption indicator is an acknowledgement of receipt of the beam failurereport.
 3. The method of claim 2, wherein the acknowledgement indicatesone or more of: an index or Cell/Carrier Indicator Flag (CIF) of theSCell, a PUCCH resource when the BFR with PUCCH is configured, or aPRACH resource when the BFR with CFRA is configured, or an index of aserving cell in which the terminal device is to perform the BFR, and/orwhen a Supplementary Uplink (SUL) carrier is configured for that servingcell, an indication of whether the SUL carrier is to be used for theBFR.
 4. The method of claim 2, wherein the acknowledgement indicates anindex of a candidate beam recommended for BFR.
 5. The method of claim 2,wherein the acknowledgement is transmitted in a Primary Cell (PCell), aPUCCH SCell, or an SCell with a configured downlink.
 6. The method ofclaim 1, wherein the method further comprises configuring the terminaldevice with a PUCCH resource pool, the PUCCH resource pool comprising atleast a first PUCCH resource, the first BFR option indicator indicatesthe BFR option of BFR with PUCCH, and the message comprising the firstBFR option indicator further comprises information indicating the firstPUCCH resource.
 7. The method of claim 1, further comprising:configuring the terminal device with a BFR priority for each servingcell based on at least one of: a carrier frequency of that serving cell,a numerology or transmission duration of that serving cell, a service orlogical channel associated with or mapped to that serving cell, atraffic load in that serving cell and whether the serving cell is aPUCCH SCell.
 8. The method of claim 1, wherein the message comprisingthe first BFR option indicator further comprises information identifyinga PRACH resource, and the method further comprise receiving a messagetransmitted by the terminal device using the identified PRACH resource.9. A method performed by a terminal device for Beam Failure Recovery(BFR), comprising: detecting a beam failure associated with a SecondaryCell (SCell); transmitting to a network device a beam failure reportassociated with the beam failure; after transmitting to a network devicea beam failure report associated with the beam failure, receiving fromthe network device a message comprising at least a first BFR optionindicator indicating one of the following BFR options: BFR with PhysicalUplink Control Channel (PUCCH); BFR with Contention Free Random Access(CFRA); BFR with Contention Based Random Access (CBRA); or BFR withoutPhysical Random Access Channel (PRACH) and PUCCH; and performing a BFRprocedure in accordance with the first BFR option indicator.
 10. Themethod of claim 9, wherein the message comprising the first BFR optionindicator is an acknowledgement of receipt of the beam failure report.11. The method of claim 10, wherein the acknowledgement indicates one ormore of: an index or Cell/Carrier Indicator Flag (CIF) of the SCell, anindex of a candidate beam recommended for BFR, an indicator of one ofthe BFR options, a PUCCH resource when the BFR with PUCCH is configured,or a PRACH resource when the BFR with CFRA is configured or an index ofa serving cell in which the terminal device is to perform the BFR,and/or when a Supplementary Uplink (SUL) carrier is configured for thatserving cell, an indication of whether the SUL carrier is to be used forthe BFR.
 12. The method of claim 10, wherein the acknowledgement isreceived in a Medium Access Control (MAC) Control Element (CE).
 13. Themethod of claim 12, wherein the acknowledgement is received in onesingle MAC CE along with another acknowledgement of receipt of anotherbeam failure report associated with another SCell.
 14. The method ofclaim 10, further comprising: starting a timer associated with theacknowledgement when the beam failure report is transmitted; andretransmitting the beam failure report upon expiry of the timer.
 15. Themethod of claim 9, wherein, when the BFR is performed in accordance withthe BFR without PRACH and PUCCH, the BFR is performed in the SCell andthe method further comprises: determining whether the BFR has succeededbased on a downlink or uplink data transmission in the SCell.
 16. Themethod of claim 15, wherein said determining whether the BFR hassucceeded based on a downlink data transmission in the SCell comprises:receiving a downlink data over a Physical Downlink Shared Channel(PDSCH); transmitting a Hybrid Automatic Repeat Request (HARD)Acknowledgement (ACK), or Non-Acknowledgement (NACK), over PUCCH inresponse to the downlink data; and determining, when an ACK istransmitted, that the BFR has succeeded when no further PhysicalDownlink Control Channel (PDCCH) is received for schedulingretransmission of the downlink data, or determining, when a NACK istransmitted, that the BFR has succeeded when Downlink ControlInformation (DCI) is received for scheduling retransmission of thedownlink data with a redundancy version value different from an initialvalue or without New Data Indication (NDI) toggling.
 17. The method ofclaim 15, wherein said determining whether the BFR has succeeded basedon an uplink data transmission in the SCell comprises: transmitting anuplink data over a Physical Uplink Shared Channel (PUSCH; anddetermining that the BFR has succeeded when no Downlink ControlInformation (DCI) is received for scheduling retransmission of theuplink data within a predetermined time period, or DCI is received forscheduling retransmission of the uplink data with a redundancy versionvalue different from an initial value or without New Data Indication(NDI) toggling.
 18. The method of claim 9, further comprising: receivingfrom the network device a configuration of a BFR priority for eachserving cell dependent on at least one of: a carrier frequency of thatserving cell, a numerology or transmission duration of that servingcell, a service or logical channel associated with or mapped to thatserving cell, a traffic load in that serving cell and whether theserving cell is a PUCCH SCell.
 19. The method of claim 9, furthercomprising, prior to said transmitting the beam failure report:transmitting to the network device a PUCCH Scheduling Request forrequesting an uplink grant for transmission of the beam failure report.20. The method of claim 9, wherein the method further comprisesreceiving a radio resource control communication identifying a PUCCHresource pool comprising at least a first PUCCH resource, the first BFRoption indicator indicates the BFR option of BFR with PUCCH, and themessage comprising the first BFR option indicator further comprisesinformation indicating the first PUCCH resource.
 21. The method of claim9, wherein the message comprising the first BFR option indicator furthercomprises information identifying a PRACH resource, and performing theBFR procedure in accordance with the first BFR option indicatorcomprises performing a random access procedure using the identifiedPRACH resource.
 22. A terminal device comprising a transceiver, aprocessor and a memory, the memory comprising instructions executable bythe processor whereby the terminal device is configured to: detect abeam failure associated with a Secondary Cell (SCell); transmit to anetwork device a beam failure report associated with the beam failure;after transmitting to a network device a beam failure report associatedwith the beam failure, receive from the network device a messagecomprising at least a first beam failure recovery (BFR) option indicatorindicating one of the following BFR options: BFR with Physical UplinkControl Channel (PUCCH); BFR with Contention Free Random Access (CFRA);BFR with Contention Based Random Access (CBRA); or BFR without PhysicalRandom Access Channel (PRACH) and PUCCH; and performing a BFR procedurein accordance with the first BFR option indicator.
 23. The terminaldevice of claim 22, wherein the message comprising the first BFR optionindicator further comprises information identifying a PRACH resource,and performing the BFR procedure in accordance with the first BFR optionindicator comprises performing a random access procedure using theidentified PRACH resource.